Johnny,
You would probably want to strip the de dion down for an inspection any way.
You may find that water has got between the inner and outer tubes and may have some rust spots on it at best.
When you strip it have a good look at the elbows as they could be damaged on the inside which could lead to failure.
I am actually considering fitting a grease nipple to my, how long would you say the life of grease is.
Colin